The present invention relates to an impact test stand for vehicle components and, in particular, for occupant restraint components.
In modern vehicles, occupant restraint systems of the most varied kind are used. In addition to belt systems with or without belt tensioners, this includes in particular inflatable protective cushions, paddings, bolsters, linings and operating parts which are deformable in an energy-absorbing manner. To optimize the protective effect, the various components of occupant restraint systems are subjected to extensive tests. Also to ensure a uniform quality in mass production, regular tests are necessary.
In order to detect all parameters which are important for the protective effect, on testing, complicated dynamic tests are necessary, which are currently carried out as so-called sliding carriage tests or real crash tests. In a sliding carriage test, a vehicle body or vehicle mock-up with the restraint system installed therein and a dummy are accelerated to a defined impact speed and driven against a defined obstacle by means of an acceleration sliding carriage. By means of sensors of the most varied kind, all the parameters which are of interest can be derived, during the impact process.
Sliding carriage tests of this type are in fact very costly, but are regarded as being necessary because the typical impact scenarios can be realistically simulated with them.
The present invention provides an impact test stand for the dynamic testing of vehicle components, in particular of components of an occupant restraint system, which enables a drastically reduced expenditure compared with sliding carriage tests, nevertheless providing a realistic simulation of impact scenarios and interactions. According to the invention, the vehicle component which is to be tested is mounted and arranged on a fixed stand, and an impact body is moved on a guide track against the component. In the impact test stand according to the invention, the vehicle component which is to be tested is held stationary, and only the impact body is moved. The impact body is representative of the shape and mass of an occupant striking on the vehicle component. By variation of mass, size and shape of the impact body, a sufficiently realistic simulation of the most frequent impact scenarios is possible.
With the test stand according to the invention, the most important functions of active restraint systems and energy-absorbing elements can be tested. In the case of inflatable protective cushions, the following can be tested in particular:
The strength of the covering of the protective cushion;
controlled outflow behavior through outflow openings or gas-permeable wall of the envelope of the protective cushion;
various tether arrangements;
various gas bag folding types;
restraint effect as a function of the compressed gas source used, e.g. a multiple-stage gas generator.
In addition, with the impact test stand according to the invention, the most varied vehicle parts can be tested as regards their energy-absorbing behavior, in particular:
steering wheels with integrated airbags;
knee cushions;
vehicle interior parts;
variants in construction and material to optimize energy dissipation.
Finally, also, basic investigation is possible regarding critical relative positions between occupants and restraint systems (OOP for Out of Position):
hit tests on various simulation arrangements (head, trunk or other body parts);
determinination of hit energy;
testing various gas bag volumes;
appraisal of various fold techniques and tether arrangements.
In the preferred embodiment of the impact test stand according to the invention, the impact body is secured in an interchangeable manner on the free end of a guide rod, which in turn is guided so as to be freely displaceable linearly in a driven sliding carriage. The sliding carriage, which is driven on an acceleration track, takes with it the impact body with guide rod, until it is braked against a stop after reaching the given speed. The impact body and guide rod are now moved further by their mass inertia and are uncoupled from the sliding carriage, so that the impact body is moved independently of the braking of the sliding carriage against the component which is to be tested, and strikes it. Through a number of suitable sensors, all the relevant parameters are detected during the impact process and are passed on to a pickup- and evaluation system.
When the component which is to be tested is an active system such as an inflatable protective cushion, activation of this system is ensured by a further sensor which detects the movement of the impact body, the travel distance and the spacing from the component which is to be tested.